Manufacture of titanium pigments



Patented Nov. 9, 1937 UNITED STATES PATENT OFFICE MANUFACW PIGMENTS I i J Roy Dahlstrom, East Orange, and Lonnie W.

' Ryan, Westfleld, N. 1., assignora by mcsne alsignments, to National Lead, Compa N w.

York, N. 1., a corporation or Jersey No Drawing.

Application 9, 1933, sci-in No. tarsus Our inve tion relates to new and useful improvements in the manufacture of titanium pigments, particularly to improvements in methods of precipitation by hydrolysis.

5 It is well-known that hydrated titanium oxide ,may be precipitated from solutions of titanium 15 solution before hydrohrsis. These nuclei shorten the time of precipitation and improve the quality of the product.

We have now. discovered a method for preparing a new type of titanium nuclei or seed mate- 20 rial. We have also discovered how it may beused to shorten greatly the time of hydrolysis of titanium sulphate solutions and to produce a product which, when calcined, has a'high degree of purity and. high hiding power when used as a pigment. 25' Furthermore, our methods are adaptable to a wide range of concentrations of titanium and acid in the solutions to be hydrolyzed.

At fairly low acid concentrations we have discovered that a precipitate can be prepared from titanium sulphate solutionswhidfi, when added to a titanium sulphate solution, greatly increases the amount oi the colloidal phase and shortens the initial period during which precipitation is not evident. Furthermore, the total time of pre- 35 cipitation is greatly shortened, and the product is very pure and fine-grained. This is obviously an economical advantage. Our novel method for preparing this precipitate, which will act as nuclei, is as follows: a A solution oi titanium is partially neutralized with an alkaline neutralizing agent, such as sodium carbonate or sodium hydroxide, after which the solution is stirred until all turbidity disappears. Then the solution is heated, with or without dilution, for'a suitable length of time at a suitable temperature.

These nuclei may also be prepared from orthotitanic acid, in which case the orthotitanic acid is dissolved in the required amount of water con- 5o taining 1% to 5% sulphuric acid and suflicient sodium sulphate or other alkalineor alkalineearth metal salts, such as sodium chloride, magnesium sulphate and sodium nitrate, to cause the orthotitanic acid to dissolve completely to a very 5 basic solution. The sodium sulphate, as well as the other'salts probably facilitate the dissolving of the orthotltanic acid by complex salt formation, but we make no claim to exact knowledge of the mechanism oi reaction involved "in this step. After the orthotitanic acid has dissolved 5 completely in the aqueous solution oi sulphuric acid and sodium sulphate or other salts, the solution is heated at a suitable temperature for a suitable length of time to precipitate the nuclei.

Our improved .method differs from existing methods of preparing nuclei for the precipitation of hydrated titanium oxide in this, that the nuclei formed are not a true colloid which disperses when added to an ilmenite solution at elevated. temperatures to form an apparently homogeneous solution. I I j Our hydrous titanium oxide nuclei are a definite microscopic precipitate which remains as such even when suspen ed in an ilmenite solution and heated to the boiling point. Our method is also different from existing processes in this respect, that the acidity or the solution from which the nuclei are prepared is much higher than heretofore used. The pH at which these nuclei are prepared is more acid than pH=2.0, that is to say, an,acid value notsubstantially less than pH=2.0 and not substantially greater than pH=1-.0.

The temperat e and time at which our nuclei are precipitated are interdependent; the higher the temperature at which the precipitation occurs the shorter the time need be. The most desirable temperature range is that between 60 C. and 100 C. Heating is continued until 85% to 95% of the titanium present is precipitated. The time" required may vary from 10 minutes to 4 hours.

After precipitation of the nuclei, it is only necessary to add the precipitate to a titanium bearing solution such as a sulphuric acid solution of ilmenite, and then hydrolyze the charge at or 4 near the boiling point until the desired yield of hydrated titanium oxide is obtained. The prodnot is then treated in the usual manner to prepare a pigment of a high degree of'purity and high hiding power.

Our nuclei precipitate is not limited in its application to the manufacture of pure titanium oxide, but may be used also in the manufacture of composite pigments siich as titanium barium pigments and titanium calcium pigments. The nuclei may be added to the titanium bearing solution either before or after hydrolysis has started,

and before, after or simultaneously with the addition of a carrier such as calcium sulphateor barium sulphate to make the composite pigments. Theme of our nuclei is also not limited to one type of titanium are eiiective at both high and low acid concentrations and in both acid and basic titanium some t ions The amount of titanium sulphate used for preparation of the nuclei may be as high as of the total solution to be hydrolyzed, but 1% or less is also effective.

Having now described our invention, we give in detail six examples, but it is to be understood that our inventionis not to be limited to the examples, which are given for illustrative purposes only.

Example I. An ilmenite solution was first 'prepared in the usual manner with sulphuric. acid analyzed: e

Percent- TiO; 6.4 H2504 20.6 F60 *Free and combined with titanium.

0f the titanium, 0.02 lb. per gallon, calculated as TiO2, wasin the trivalent state. To 123 pounds sulphate solution. The nuclei of this solution (15% by weight of the total solution to be used forprecipitation), 13.7 pounds of v sodium carbonate (equivalentto 50% of the sulphuric acid, free and combined with titanium) was added during constant agitation. Suflicient water (60 gallons) was'then added to reduce the The solution became turbid as the sodium carbonate was added, but upon stirring it soon became clear again. Agter the solution was clear, it was heated to 1 0 minutes to precipitate the desired nuclei. The solution was then allowed to cool and settle, after which the clear liquor was removed by decantation. The precipitate was added to the main portion of the ilmenite solution (697 pounds"), and

the whole was boiled 11 hours until about 95% of the titanium'was' precipitated, The precipitate was then'filtered, washed and calcined. A

similar solution, boiled without first adding nuclei,

yielded after 11 hours, a precipitate of less than 40% of the titanium. 1

Example II.. An ilmenite solution, from which a part of the iron had been removed by crystalminutes.

lization as ferrous sulphate, analyzed as follows:

Percent to 8.15 pounds of the a precipitate was filtered I of barium sulphate.

. I aoeaeve a part of the iron had been removed by crystallization as ferrous sulphate, analyzed as follows:

Of the titanium, 0.02 lb. per gallon calculated 2 was in the trivalent state. Orthotitanic acid was precipitated by adding 1.44 pounds of sodium hydroxide dissolved in 10 gallons of water and washed. It was then dissolved in an aqueous solution of ve ilmenite solution; The

0.40 pound of sulphuric acid and 2.3 pounds ofv sodium sulphate.

The total weight or the titanium solution was 26.2 pounds. The solution analyzed: I

I I Percent T10: 4.0 NazSO4 9.0 H2804-.. 1.6

The pH was 1.5. V to 85 C. and held at that temperature for 90 At the end of this time about 95% oi the titanium was precipitated in a form suitable for use as with its mother liquor was then added-to 407 pounds of the same solution as that used for the precipitation of the orthotitanic acid. This solution, containing the nuclei, was heated to boiling and boiled for two hour-sat which time 95% of the titanium present was precipitated. The precipitate was filtered and washed and calcined in the usual manner.

The solution was then heated nuclei. The nucleiprecipitate together.

Example IV.An ilmenitesolution, from which a part of the iron had been removed by crystal lization as ferrous sulphate, analyzed .as follows: 1 i Percent T10: 12.20 FeO 3.70 H2304 21.60 *Free and combined with T102.

01' the titanium, 0.02 lb. per gallon. calculated as TiOz, was in the trivalent of this solutiqn was added 195 pounds 01' an aqueous blanc fixe pulp containing 150 pounds This suspension was boiled for 30 minutes, after which nuclei which had been prepared-as described under Example III were T102 10;6 FeO 2.0 Bison"... 1 31.3

- lowed to cool and settle.

' cc and combined with titanium.

j filtered and washed and ions of water (equivalent to of the sulphuric acid, free'andcombined with titanium) was added during constant agitation. had an acidity of 2.5%. came clear, it was boiled The solution then -After this solution befor 15 minutes, then al- The supernatant liquid was decanted, and the precipitate mixed with 456.2 pounds of the sulphate solution. to be precipitated by hydrolysis. After boilingfor about 3 hours 95% of the total titanium present was precipitated. The precipitate-was filtered, washed and calcined in the usual manner.

Example llL- -An ilmenite solution, from which containingmagnesium sulphate dissolved added to the extent of 1% of the total titanium oxide to be precipitated by hydrolysis. After 3 hours"boiling, about95% of the titanium was precipitated. The composite precipitate was then manner. I

Example V.The following procedure will 11- lustrate how the nuclei may be prepared by the use oi sodium chloride.

To S'gal. of water, 0.6 lb. of sulphuric acid and 10 lb. of sodium chloride were added. Orthotitanic acid equivalent to 2 lb. of TlOa was dissolved in this solution, and the nuclei were precipitated by heating .for 4-5 hours at 80 'C. The nuclei were then used in the precipitation of titanium in the same way as described in Example IIIQ. I 1

Example VI.-As"to the use of magnesium sulwas 1.8 lbs. in was the same 50 lb. of solution. The procedure as in Example V. v The solution the orcalcined in the usual state. To 432 pounds 1 equivalent to 2.0 lb. 'IlOa was added to be dissolved. 7

In the appended claims the compounds which aid. the solution of orthotitanic acid in the presence of a small amount of free acid will be ge-' nerically designated as alkaline and'alkalineearth metal salts".

We claim as our invention: v

1. A method of hydrolyzing a sulphuric acid solution of ilmenite, which comprises adding to said solution therein permanently insoluble macro'scoplc hydrous titanium oxide'nuclei obtained by thermal hydrolysis of a sulphuric solution of titanium having a hydrogen ion concentration of pII' 1.0 to pH=less than 2.0, and then heating said ilmenite solution containing said nuclei.

2. A method of hydrolyzing 'a sulphuric acid solution of ilmenite, which comprises heating a sulphuric acid solution of orthotitanic acid having a hydrogen ion concentration oi pH=l.0 to pH==less than 2.0 at a suiliciently high temperature and for a sufllcient length of time to precipitate by hydroh'sis permanent macroscopic hydrous titanium oxide nuclei, adding the resulting nuclei to asulphuric acid solution of ilmenite, and heating said ilmenite solution containing the therein permanently insoluble nuclei.

3. A method of hydrolyzing a sulphuric acid solution of llmenite, which comprises heating a sulphuric acid solution 01' alkali-precipitated titanium compounds having a hydrogen ion concentration or pH=l.0 to pH =less than 2.0 at a suiiiciently high temperature and for a suflicient length of time to precipitate by hydrolysis perman'ent macromopic hydrous titanium oxide nuclei, adding the resulting nuclei to a sulphuric acid solution of ilmenite, and heating said 11.- menlte solution containing the therein permanentlyinsoluble nuclei.

4. In a method of hydrolyzing a sulphuric acid solution of ilmenite, the step which consists in.

heating a sulphuric acid solution of ilmenite containing therein permanently insoluble macroscopic hydrous titanium oxide nuclei obtained by thermal hydrolysis of a sulphuric acid solution of titanium having a hydrogen ion concentration of pH=1.0 to pl-I=less than 2.0.; g

5. A method of producing hydrous titanium .oxide nuclei for the manufacture of titanium pigments, which comprises adding an alkaline neutralizing agent to a titanium sulphate solution, redissolving in the mother liquor theresulting alkali-precipitated titanium compounds, adjusting the hydrogen ion concentration of the resulting solution from pH: 1.0 to pH=less than 2.0, and then heating the solution. at a sufllciently high temperature and for a sufllcient length of V time to precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide nuclei. .6. A method of producing hydrous titanium oxide nuclei for the manufacture of titanium pigments, which comprises addingan alkaline I neutralizing agent to a titanium sulphate solution, redissolving in the mother liquor the resulting. alkali-precipitated titanium compounds, ad lusting the hydrogen ion concentration of the resulting solution from pH= 1.0 to pH=less than 2.0, and then heating the solution at temperatures between 60 C. and 100 C. for from ten minutes to tour hoursto precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide fnuclei.

'I. A method of producing hydrous titanium oxide nuclei from the manufacture of titanium pigments, which comprises dissolving alkali-precipitated titanium compounds in an aqueous solution of a compound selected from the group consisting of sodium sulphate, magnesium sulphate, sodium chloride and sodium nitrate containing .suilicient sulphuric acid after dissolution oi said alkali-precipitated titanium compounds, to"cause the resulting solution to have a hydrogen ion concentration of pH=l.0 to pH=lessthan 2.0, and then heating the solution at a sufllciently high temperature and for a suflicient. length oi} time to precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide nuclei.

8. A method of producing hydrous titanium oxide nuclei for the manufacture of titanium pigments, which comprises dissolving orthotitanic acid in an aqueous solution of a compound selected from the group consisting of sodium sulphate, magnesium sulphate, sodium chloride and sodium nitrate containing suiilcient sulphuric acid after dissolution of said orthotitanic acid to cause the resulting solution to have a hydrogen ion concentration of pH=l.0 to pH=less than 2.0, and then heating the solution at a suiliciently high temperature and. for a sufllcient length 01' time to precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide nuclei.

9. A method of producing hydrous titanium oxide nuclei for the manufacture of titanium pigments, which comprises dissolving alkali-precipitated titanium compounds in an aqueous solution of a compound selected from the group consisting of sodium sulphate, magnesium sulphate,

sodium chloride and sodium nitrate containing suificient sulphuric acid after dissolution of said' alkali-precipitated titanium compounds to cause the resulting solution to have a hydrogen ion concentration of pH=l.0 to pH=less than 2.0, and then heating the solution at temperatures between C. and 100 C. for from ten minutes to four hours to precipitate thereinby hydrolysis permanent macroscopic hydrous titanium oxide nuclei.

10. A method of producing hydrous titanium oxide nuclei for the manufacture of titanium pigments, which comprises dissolving orthotitanic acid in an aqueous solution of a' compound selected from the group consisting 01- sodium sulphate. magnesium sulphate, sodium chloride and sodium nitrate containing sufllcient sulphuric acid after dissolution of said orthotitanic acid to cause the resulting-solution to have a hydrogen ion concentration pH=l.0 to pH=less than 2.0, and then heating the solution at temperatures" between ,'60 C. and 100 C. for from ten minutes to four hours to precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide nuclei. 11. A method of producing hydrous titanium oxide nuclei for the manufacture oi titanium pigments, which comprises dissolving alkali-precipitated titanium compounds in an aqueous solution of sulphuric acidcontaining a compound selected from the group consisting of sodium sulphate, magnesium sulphate, sodium chloride and sodium nitrate, adjusting the hydrogen ion concentration thereof from p=H 1.0 to pH=less than 2.0, and then heating the-solution at a sufflcient high temperature and for a sufficient length of time to precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide nuclei.

12. In a method of producinghydrous titanium Patent No 2,o98,278.-

aqueous solution of 'sulphric acid and a compound selected from the group consisting 0! so- RoY DAHLSTROM, ET AL.

time to precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide nuclei.

15. In a method ot producing hydrous titanium oxide nuclei, the step which consists in heating a solution of orthotitanic acid having a hydrogen November 9; 3.957. g

It is hereby certifiedthat err r, appearsfin the printed specification '5 dium sulphate, sodium chloride, magnesium sul- 5 phate and sodium nitrate to dissolve said'alkaliionconcentration o1 pH=1.0 to pI-I=iess than 2.0 precipitated titanium compounds therein. at a sufllciently high temperature and for a sum- 13. In a method of producing hydrous titanium cient length of'time to precipitate therein by hyoxide nuclei, the step which consists in mixing drolysls permanent macroscopic hydrous titanium o orthotita'nic acid and an aqueous solution of suloxide nuclei. 1o

phuric acid and a compound selected from the 16. In a method of producing hydrous titanium group consisting ofsodium sulphate, sodium chlooxide nuclei, the step which consists in heating a ride, magnesium sulphate and sodium nitrate to solution of orthotitanic acid having a hydrogen dissolve said orthotitanic acid therein. ion concentration of pI-I=1.0'to pH=1.5 at a sum- 15 14. In a method of producing hydroustitanium ciently high temperature and for a suificient 15 oxide nuclei, the step which consists in heating a; length of time to precipitate therein by hydrolsolution of alkali-precipitated titanium comysis permanent macroscopic hydrous titanium pounds having a hydrogen ion concentration of oxide nuclei. pH=1.0 to pH=1ess than 2.0 at a sufllciently ROY DAI-ILSTROM'.

20 high temperature and for. a suillcient length of LONNIE W. RYAN. 20

I CERTIFICATE OF CORRECTION.

. of the above numbered patentrequiring correction as follows; Page 1 second column, line 18, for the word "microscopic" read macroscopicfi'and that the said Letters Patent should be read with this correction" thereinithat-the ;same may conform to the record theicase in the Patent Office.

Signed and sealed (Seall this 1st day of February, A. D. 1958.

Henry VanArsdale, Acting Commissioner 'of Patents.

Patent No 2,o98,278.-

aqueous solution of 'sulphric acid and a compound selected from the group consisting 0! so- RoY DAHLSTROM, ET AL.

time to precipitate therein by hydrolysis permanent macroscopic hydrous titanium oxide nuclei.

15. In a method ot producing hydrous titanium oxide nuclei, the step which consists in heating a solution of orthotitanic acid having a hydrogen November 9; 3.957. g

It is hereby certifiedthat err r, appearsfin the printed specification '5 dium sulphate, sodium chloride, magnesium sul- 5 phate and sodium nitrate to dissolve said'alkaliionconcentration o1 pH=1.0 to pI-I=iess than 2.0 precipitated titanium compounds therein. at a sufllciently high temperature and for a sum- 13. In a method of producing hydrous titanium cient length of'time to precipitate therein by hyoxide nuclei, the step which consists in mixing drolysls permanent macroscopic hydrous titanium o orthotita'nic acid and an aqueous solution of suloxide nuclei. 1o

phuric acid and a compound selected from the 16. In a method of producing hydrous titanium group consisting ofsodium sulphate, sodium chlooxide nuclei, the step which consists in heating a ride, magnesium sulphate and sodium nitrate to solution of orthotitanic acid having a hydrogen dissolve said orthotitanic acid therein. ion concentration of pI-I=1.0'to pH=1.5 at a sum- 15 14. In a method of producing hydroustitanium ciently high temperature and for a suificient 15 oxide nuclei, the step which consists in heating a; length of time to precipitate therein by hydrolsolution of alkali-precipitated titanium comysis permanent macroscopic hydrous titanium pounds having a hydrogen ion concentration of oxide nuclei. pH=1.0 to pH=1ess than 2.0 at a sufllciently ROY DAI-ILSTROM'.

20 high temperature and for. a suillcient length of LONNIE W. RYAN. 20

I CERTIFICATE OF CORRECTION.

. of the above numbered patentrequiring correction as follows; Page 1 second column, line 18, for the word "microscopic" read macroscopicfi'and that the said Letters Patent should be read with this correction" thereinithat-the ;same may conform to the record theicase in the Patent Office.

Signed and sealed (Seall this 1st day of February, A. D. 1958.

Henry VanArsdale, Acting Commissioner 'of Patents. 

